Once an amateur boxer, he had grown up determined to become a professional footballer and in his youth he wrote to clubs across England asking for a trial. He didn't get one, but took up the chance to play in his own country with Cobh Ramblers. He quickly impressed, and in June 1990 he was signed by Nottingham Forest of the old First Division in England.

At Forest, Keane improved further, appearing twice in Wembley cup finals and playing his first games for the Republic of Ireland. In July 1993 he was signed by champions Manchester United for £3,750,000, then a British transfer fee record. At first he appeared somewhat out of sorts, playing in various positions before setting into central midfield, a role then dominated by the duo of Bryan Robson and Paul Ince.

United continued to win trophies and when both Robson and Ince had left by the summer of 1995, Keane became the key central midfielder and a player of much importance in the side. Though his skill was growing fast, so was his reputation as a tough and violent player. He entered into challenges with more bite than many, and frequently made the mistake of talking back to referees, two traits that earned him his fair share of bookings and red cards. In 1995 he was banned for three matches and fined £5,000 for stamping on England defender Gareth Southgate during an FA Cup semi-final.

Loved by United fans and the Irish, often derided by the rest of the country, Keane went through his lowest phase of popularity around 1996-97. Summing up his less-than-godlike status among English supporters, Total Football magazine printed a letter on an unrelated topic that ended with the postscript: "If I say that Roy Keane is a wanker with the IQ of a paving slab and the footballing ability of a piece of toast, does this letter get printed?" "Of course it does."

There has however no doubting his ability and ferocious commitment, and in 1998 the BBC's more staid Match of the Day magazine judged him to be the best player in the country. He missed most of season 1997-98 through injury, but impressed greatly in the following two seasons and was made captain of Manchester United after the departure of the legendary Eric Cantona. Though he missed United's victorious 1999 Champions League final, he won both the PFA and Football Writers' awards for Player of the Season the following year.

United won the championship again in 2000-01, although Keane rather dented his popularity with outbursts against the team's corporate fans - more interested in "eating prawn sandwiches" than watching the team - and against the commitment of some of the club's own players.

They failed to retain their league title in 2002, but as if that wasn't enough, the lowest point in Keane's career came barely a month later at the end of May, in what should have been the beginning of a summer to remember. Selected as captain of Ireland's squad for the 2002 World Cup in Japan and South Korea, he was sent home days before the start of the tournament in circumstances so controversial they reached the front pages of the broadsheets.

After criticising Ireland's training staff and the facilities allocated to the team, he announced he would return home. He changed his mind on the advice of United manager Alex Ferguson, but insisted he would retire from international football after the World Cup was over. Ireland coach Mick McCarthy called a meeting of the entire squad to let any grievances be aired. As the Guardian newspaper reported on the 25th May 2002:

Just one voice, Keane's, was raised. He said: "Who the fuck do you think you are, having a meeting about me? You were a crap player, you are a crap manager. The only reason I have any dealings with you is that somehow you are manager of my country and you're not even Irish, you English cunt. You can stick it up your bollocks." Keane then walked out of the meeting.

Such bewildering ignorance of the male anatomy left McCarthy with no choice but to send Keane home, thus committing him to spending the entire World Cup with journalists camped outside his garage. His absence did not prevent the squad from playing a respectable, if not dazzling, World Cup performance, and in August McCarthy made it clear that he was not going to invite Keane back in the near future.

Keane's nightmare summer got even worse later that August when Manchester City, United's rival club, announced they were going to sue Keane for a tackle he had made on City midfielder Alf-Inge Haaland in a game 16 months previously. The tackle had caused an injury threatening to end Haaland's career, but he only decided to take action in 2002 after learning that the tackle had been an act of revenge on Keane's part. As Keane himself rather candidly put it in an excerpt from his forthcoming autobiography, inheriting the mantle of literary splendour for which Ireland has long been renowned: "I'd waited long enough. I fucking hit him hard. The ball was there (I think). Take that, you cunt. I didn't wait for [referee] Mr Elleray to show the card. I turned and walked to the dressing room."

Keane survived the summer but in February 2003 he finally confirmed what everyone had expected anyway and announced his retirement from international football. After 58 games and nine goals as one of the most popular players in recent Irish history, Keane is now free to concentrate on the United team struggling to overtake Arsenal in the race for the 2003 Premiership title.